October 2012
 Distributed by The Nature Conservancy's Global Marine Initiative

Ramsar Convention on Wetlands: A new opportunity for international conservation of bivalve reefs

The Convention on Wetlands of International Importance was created in 1971 to help curb the accelerating loss of wetlands globally, and to increase international collaboration on wetland conservation overall. Dubbed the"Ramsar Convention" after the Iranian city in which it was drafted, it is the only international policy agreement that focuses exclusively on promoting the wise use and protection of the world's wetlands. At present, there are 163 signatory countries working collaboratively to protect wetlands at 2,053 designated Ramsar Sites covering nearly 194 million hectares (approximately 480 million acres). How is this related to shellfish and bivalve habitat like oyster reefs?

One of the key recommendations in a recent global assessment of oyster reef condition (Beck et al. 2011) was to protect bivalve reefs under international agreements such as the Ramsar Convention. Wetlands are defined rather broadly under the convention, and the list of eligible wetland types includes other structured aquatic habitats such as coral reefs down to 6 meters depth, but until recently did not specifically include bivalve reefs. Over the past two years, scientists from The Nature Conservancy worked closely with the Ramsar Scientific and Technical Review Panel (STRP) to compile the necessary information to support bivalve reefs being included among the list of wetland types eligible for nomination as a Ramsar Site. Fortunately, the STRP was in the process of updating the nomination materials including the Ramsar Information Sheet (RIS) that countries use to nominate new sites, so the timing was perfect for making this addition to the list. In July 2012, the Convention's signatory countries convened at the 11th triennial Conference of Parties (COP-11) in Bucharest, Romania and passed a resolution to adopt the RIS with its updated list of eligible wetland types. This revised data sheet will be available for voluntary use by countries as early as April 2013 after some final formatting details are addressed. While this addition to the list of wetland types may seem a relatively small change, it represents a huge new opportunity for countries to nominate and protect new sites that have bivalve reefs at their core. Such increased international attention and collaboration could be a powerful way to reversing decades of loss that have all but eliminated oyster reefs from some regions of the world.

Oyster Filtration Past and Present: Putting Numbers on Ecosystem Services.

Oyster reefs provide a suite of valuable ecosystem services, from enhancing fisheries production through to providing coastal protection. But quantifying those services is frequently challenging, and none more so than the service of water filtration. While there are many laboratory based measurements, few studies have attempted to quantify this service in the field, where conditions are variable and frequently suboptimal. Such quantification is, however, a critical next step for both restoration and management.

A new study led by TNC and published this month in Estuaries and Coasts provides many of the answers. The scientists involved used field based measurements to build a model for estimating the volume of water filtered by oyster populations in the field. They then used this model and data on the historical and modern oyster populations from an earlier publication to estimate the volume of water filtered historically (c. 1900) and presently in 13 estuaries around the East and Gulf coasts.

The study reveals that oyster filtration declined in 12 of the 13 estuaries examined, and by a mean of 85%. This is likely to have had a significant effect on the ecology of impacted estuaries. For example, whereas in Matagorda Bay TX, the oyster population historically filtered a volume equivalent to 320 Fenway Park stadiums an hour, it now filters just 2. This estuary is just 1 of 6 in the Gulf of Mexico in which the historic oyster population was capable of filtering the full volume of the estuary within its residence time; an indication that filtration by oysters was historically a dominant force. Now, only one of the 8 estuaries examined in the Gulf of Mexico achieves this feat.

Filtration is a valuable ecosystem service. By increasing the water clarity, oyster filtration promotes the growth and recovery of seagrasses, which themselves also have a high economic value, as highlighted in another recent study.

But it isn't all bad news. The study also highlights some bright spots for management, with Apalachicola Bay showing an increase in filtration pressure from historic; evidence that with sound management of oyster reefs and river flows (ever more critical given regional water management challenges), it is possible to maintain an oyster population capable of providing significant ecosystem function and a productive oyster fishery.

By providing an insight into the ecological impact of the historic and present oyster population, this study helps identify estuaries where large scale impacts of oyster filtration have been lost. More critically still, it creates a framework for estimating the amount of restoration required to bring oyster back to the level where they can once again provide this important service at a large scale.

Funding support for this study was provided by the National Fish and Wildlife Foundation (NFWF), the National Partnership between TNC and NOAA Restoration Center, The Turner Foundation and the TNC-Shell Partnership. For more information, please contact Dr. Philine zu Ermgassen.

Upcoming Events and Conferences


Northeast Aquaculture Conference & Exposition/Milford Aquaculture Seminar/International Conference on Shellfish Restoration Special Joint Meeting
Aquaculture and Restoration: A Partnership
December 12-15, 2012 Mystic Marriott Hotel & Spa Groton, CT

Note:  If you would like to contribute an article or submit items for the "Looking Ahead" section, please contact Boze Hancock.

Oyster Restoration Publications and Resources

Oyster Restoration Working Group Research and Reports

The Practitioner's Guide to Shellfish Restoration: An Ecosystem Services Approach, as well as back issues of the Shellfish Restoration Clamor are available online.

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